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Tue Jun 14, 2011 2:16 am

Guys,

friend of mine has a W120 cam and he needs new rocker arms.
I told him that for the w series cam rocker arms that can be used are the stock types or the 1.25 rockers.

He called a vw store where he orders his stuff and there they told him he can use the 1.4 rockers too.

Is this possible and if yes what would his gain be over the 1.25 rockers?

He runs hi rev single heavy duty springs btw,could he run them(the 1.25 rockers) with the w120 cam(car wont see hi revs as it will be used for daily driving and some freeway driving)?

As advice should he go with the 1.25 rockers or go with the 1.4 or should he stick to the stocktype rockers with his setup above?

Greets,
Stanford

Tue Jun 14, 2011 5:45 am

If you go to Engles web site they show that the W series cams, can only use 1.1 or 1.25 rockers not 1.4's

Tue Jun 14, 2011 6:07 am

I would not run 1.25 rockers on a W-120 with single springs. 1.4 would be asking for disaster..

Tue Jun 14, 2011 6:26 am

The ramp angles when combining W series cams and 1.4 rockers are too violent and it takes too much spring to keep the lifters tracking the cam properly. Any time you can move the valve more quickly above 0.050" lift it will make more power and it will work for a while, but will eventually break parts. I believe Gene Berg documented accelerated guide and stem wear, seats being pounded into the head, bent pushrods, accelerated lobe, lifter and lifter bore wear when using 1.4's with cams designed for stock rockers.

On the other hand, if your friend has ported heads then 1.25 rockers will give enough lift to use the porting work that he paid for and not be too hard on the heads and valve train. More lift will provide more power throughout the rpm range. I have spoken to Jack Engle (through the magic of Email; gotta love this electronic age. Think of what we're doing right now! :lol: ) and he confirmed their W series cams could be run with 1.25's safely.

The only caveat here is with this much lift (close to 1/2" vs .430" or so) there should be dual springs installed. Some guys run that much lift with only single springs and again it works short term, but John at aircooled.net, the Bergs and a lot of head porters and engine builders will tell you that the same damage that happens with too much ratio rocker also happens with not enough spring pressure for cam/rocker combo. The valve is literally thrown into max lift (the Porsche 356 4 cam motors did this for more lift without breaking parts) and because the spring is not controlling it properly, slams the lifter onto the return side of the lobe. You will see wear on the return ramp of the lobe and I think people well versed in camshaft technology call it "lofting". The valve also hits the seat hard instead of a controlled, more gradual closing. This all does the same kind of damage as described above, pounding seats, accelerating guide, stem and valve face wear (and even breaking valves), bending or breaking pushrods, damaging the lobe/lifter contact surface and accelerating lifter bore wear.

Just my 2 1/2 cents (I'm Canadian, eh). Al

Tue Jun 14, 2011 6:45 am

Guys,

thnx for the advice.I told my friend that he can use the 1.25 rockers if used with dual spring setup,but could it be run with just the heavy duty single springs or is this a big no no?

Btw his heads are not p&p,just plain 40x35.5 ss valved heads from scat i guess.

Greets,
Stanford

Tue Jun 14, 2011 8:58 am

yes no maybe,and check for coil bind.

Tue Jun 14, 2011 9:11 am

Whatever you do....DO NOT run the 120 with 1.4's unless this is a race only "who cares" engine and it would need not just dual springs but real good ones like VW650's from CB or some K800's even.
With 1.25's you are in a gray area of single or dual springs and when in doubt....dual it out.

Tue Jun 14, 2011 9:29 am

Bewitched wrote: but could it be run with just the heavy duty single springs or is this a big no no?
Btw his heads are not p&p,just plain 40x35.5 ss valved heads

The W120 cam should be run with dual valve springs regardless of rocker arm ratio, 1.1:1 or 1.25:1. Like vwracerdave said, using 1.4's on a W120 is asking for disaster. 'They' always say "I'm only using it on the street, no racing" or " I'll never rev the engine above 5k" :roll: That's only half the story guys. Let's assume you actually never will see over 5k, that's fine (although it's really a waste of a W120 cam IMHO), but high revs are not the only reason for running dual valve springs. The cam and other parts like carbs, heads, exhaust, lightened flywheel, etc. will allow the engine to rev much faster than a stock engine ever could. This is just as important as having good valvetrain control at high revs. People don't realize valve float can occur at lower revs too, as low as 3500 RPM. Single springs can't control these quicker revs. So unless you drive, literally with an egg under the gas pedal, you are leaving the engine open to damage. It's not my engine though so if you want to listen to someone who says 'Yeah just run singles, they will work fine'............your choice.

The other thing you may not be aware of is in your heads. 40 x 35.5mm valves, when installed without portwork and probably just a standard single angle valve job, provide very little gain in performance. In fact a well ported set of 35.5 x 32mm heads will outperform them. Port your heads and with dual springs you will be able to see what the W120 cam can really do for performance.

Wed Jun 26, 2013 7:12 am

I'm bringing this old thread back up because at least the title applies to what I'm doing.

I'm gathering up parts for a 2110cc engine. It's going to have dual 44 HPMX carbs, Engle 120 cam & new Engle lifters, H-beam rods, AA pistons/cylinders, new AS41 case, 1.25:1 rocker arms, heads and exhaust are undecided yet, but there will be some port work & dual springs. It'll be used in my completely street driven kit car. More of a daily driver than not. RPM will usually be kept below 5500 but there might be an occasional blast to 6500 max.

My spare (basically stock) motor has a set of solid rocker shafts in it. Don't remember the brand for sure but it might be BugPack. I bought the shafts 17 or more years ago. The rocker arms on that motor also have a set of Porsche style adjusters on them that I could pirate for this motor. I've had them for at least 20 years (and put quite a few miles on them with no problems) so I'm guessing they're a better quality set than a lot of those available today. They're the type that uses an allen wrench to adjust them if that makes any difference.

I had planned to buy a CB Performance Super Stock 1.25:1 rocker arm/shaft kit but they're on back order ( so are the bare rocker arms, and it seems like they have been forever :roll: ) and it looks like they may never be back in stock so I thought I'd ask for recommendations, either a kit with shafts or just a set of arms that I can swap over with the parts I have.

It might be worth mentioning that cip1 is having a 20% off sale this month but I'm certainly willing to buy from other vendors. :)

Wed Jun 26, 2013 8:43 am

aircooled.net has 2 options for u

the swipe rocker style set in 1.25s

and the OEM style 1.25s

check em out , they usually ship quick and have em in stock :)